JPS6022990B2 - How to paint the inner surface of a pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a treatment method for making a paint layer applied to the inner surface of a pipe body uniform and smooth without variation in film thickness.

Conventionally, the method of coating the inner surface of a long pipe with a thick film is to insert a nozzle into the long pipe and rotate the nozzle or the long pipe in the direction between the ends of the nozzle. A method has been implemented in which the inner surface is coated by moving the tube in the length direction.

In addition, as a method of painting a thick film on the inner surface of a long tube with a medium diameter, the inner surface is coated by spraying paint in a circular shape from a nozzle inserted into the long tube and moving the nozzle in the length direction of the longest tube. is being carried out. When painting the inner surface of a long tube with a small diameter using this method, it is difficult to set the distance between the nozzle and the inner surface of the tube appropriately, and because the distance is 4. There is a problem in that the appearance of the coating is significantly deteriorated due to the large effect of

For this reason, either the spray pressure of the paint is reduced and two or more layers are applied, or even if such layers are applied,
As the number of applications increases, the smoothness of the resulting paint film deteriorates.
Moreover, a drying process of about 2 hours is required for each coating, and it takes a great deal of time and effort to commercialize the product. On the other hand, after applying a thick coating to the inner surface of the tube, the tube was restored between a pair of rotating rollers in order to improve the appearance of the coating.
Is there a method in place to apply high-speed rotation in the circumferential direction and use the resulting centrifugal force to smooth the paint film?The paint film applied to the inner surface of the pipe has an uneven surface both in the circumferential direction and in the length direction. Even if the pipe is subjected to high-speed rotation in all directions around the circumference, paint movement only occurs in the circumferential direction. Therefore, even if the uneven surface in the circumferential direction can be smoothed, the uneven surface in the longitudinal direction remained as it was, and when the inner surface of the tube was viewed from the entrance at one end, there were drawbacks such as continuous annular unevenness in the length direction.

In order to eliminate such drawbacks, the present invention provides a pipe characterized in that a pipe body coated with an inner surface is rotated at high speed in the circumferential direction while the paint layer is not dried, and shocks or vibrations are applied to the pipe body. The present invention provides a method for painting the inner surface of a body.

An embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a machine base comprising a plurality of pairs of left and right rotating rollers 2 and 3, with small intervals between loaves arranged at appropriate intervals on the same horizontal straight line; A shaft 4 driven by a motor is rotatably supported,
The rotation of the shaft 4 is transmitted to each roller 2 via a pulley and a belt 5.

Reference numeral 6 denotes a support frame disposed above the rock platform 1, on which air cylinders 7 are sequentially attached in a vertical direction corresponding to the upper part between the rotary rollers 2 and 3, and the piston rod 7a of the air cylinder 7 The rotation center axis is at the lower end of the rotating roller 2,
A pinch roller 8 parallel to the central axis of 3 is rotatably supported.

As shown in FIG. 3, this pinch roller 8 has an outer circumferential surface formed in a regular polygonal shape such as a regular elevation angle or a regular hexagonal shape, or an irregularly shaped roller having a portion cut out 9 over its entire length. Now, the 6th
As shown in the figure, a spray gun 11 is inserted into the inside of a long steel pipe 10 with a small diameter, and a solvent-based resin paint such as tarepoxy resin paint is jetted out in a circular shape from the spray gun 11. A coating film 12 is formed on the inner surface of the steel pipe while moving it in the length direction of the steel pipe 10. After the coating film 12 is applied to the inner surface of the steel pipe in this way, the steel pipe 10 is immediately placed between a plurality of pairs of rotating rollers 2 and 3, and the air cylinder 7 is operated to bring the pinch roller 8 into contact with the upper surface of the outer periphery of the steel pipe 10. In this state, the rotary rollers 2 and 3 are rotated to rotate the steel pipe 10 at high speed in the circumferential direction, applying a centrifugal force of 2 or more to the coating film 12, and further, as the steel pipe 10 rotates, the steel pipe 10 is rotated at a high speed. A pinch roller 8 in contact with the outer peripheral surface of the pipe 10 is rotated in a circular motion, and its outer peripheral corner 8a applies an impact to the steel pipe 101 at a rate of 50 times/second or more.

In this way, when a constant impact is applied to a high-speed rotating steel pipe, centrifugal force causes the inner coating film 12 of the steel pipe 10 to flow to a uniform film thickness in the circumferential direction, and the impact spreads over the length of the steel pipe 10. The vibration force is transmitted in the longitudinal direction, and the paint on the coating film 12 also moves in the tube axis direction, so that the coating film 12 on the entire inner circumference is leveled to a uniform thickness. In addition, the steel pipe 10 rotating at high speed
In addition to the above-mentioned embodiments, as a means for applying impact or vibration to the steel pipe, for example, a relatively fine continuous wave shape or a large number of uneven stripes may be formed continuously in the circumferential direction on the outer circumferential surface of the pinch roller 8. Alternatively, as shown in FIG. 5, the pinch roller 81 may be a multi-circular one, and one rotating roller 3 may be an irregularly shaped roller such as a regular polygon. In addition, the pinch roller 8
Alternatively, one of the rotating rollers may be formed into an irregularly shaped roller, or the roller may be eccentric to generate the vibrating force.

Furthermore, it goes without saying that the method for painting the inner surface of a steel pipe according to the present invention can be applied not only to small-diameter pipes but also to large-diameter pipes. Next, specific examples and comparative examples of the present invention will be shown.

Example 1 After coating the inner surface of an 80A x 5.5 skin steel pipe (JIS○3452) with a tar epoxy resin paint using a spray gun to form a coating film with an average film thickness of 420 mm, the steel pipe was immediately placed on a plurality of pairs of rotating rolls. Remount it and make a diameter of 4
A plurality of regular square pinch rollers on the third side were pressed and the rotary roller was rotated for 6 seconds at 1050 times/min.

The centrifugal force applied to the coating film at this time was about 5 degrees, and the number of impacts was 350 times/second. The coating film on the inner surface of the steel pipe treated in this manner had a smooth surface with a uniform thickness both in the circumferential direction and the length direction, and had a good appearance. Comparative Example 1 A coating film was applied to a steel pipe having the same shape as in Example 1 under the same conditions, and then the coating film was cured without being subjected to rotation or impact.

This coating film showed significant irregularities both in the circumferential direction and in the longitudinal direction of the steel pipe.

Comparative Example 2 After a coating film was applied to a steel pipe having the same shape as in Example 1 under the same conditions, the steel pipe was rotated at a speed of 105 m/min at a speed of 9 by rotating a rotary roller while being held down by a perfect circular pinch roller. Ta.

The exposed surface of the thus obtained coating film was formed to have a substantially uniform thickness in the circumferential direction, but an uneven surface was formed in the ball tube direction.

Example 2 After coating the inner surface of a 4M x 5.5 steel pipe in the same manner as in Example 1 to form a lepoxy resin coating with an average film thickness of 350 m, the steel pipe was immediately coated on a rotating roller at 1700 times/min. Rotated for 4 seconds.

During this rotation, a regular la square pinch roller with a diameter of 45 ribs was brought into pressure contact with the steel pipe, and as the steel pipe rotated, it was rotated in a circular motion to apply impact blows to the steel pipe at 360 times/second.

The centrifugal force applied to the coating on the inner surface of the steel pipe was approximately 67G. The coating film on the inner surface of the steel pipe treated in this way was formed to have a substantially uniform thickness over the entire circumference and length.

Comparative Example After applying a coating film under the same conditions to a steel pipe with the same shape as in Example 2, the coating film was allowed to harden without applying any rotation or impact. Irregularities were visible.

As described above, the present invention rotates a tube body coated on the inner surface at high speed in the circumferential direction while the paint layer is not dry to apply a centrifugal force of 2 eaves or more to the paint layer and to rotate the tube body 50 times/sec. Since this method relates to the method for painting the inner surface of a tube, which is characterized by applying the above-mentioned impact or vibration, the coating film applied to the inner surface of the tube increases in thickness in all directions around the circumference due to the high-speed rotation of the tube. At the same time that the paint is evenly leveled, the flow of the paint at that time also moves in the direction of the rattan pipe due to the propagation of impact force or vibration force in the length direction.
The thickness of the coating film is made uniform over the entire circumference and length of the tube, making it possible to obtain a coating on the inner surface of the tube with excellent smoothness in a short time. It is something.

[Brief explanation of drawings]

The drawings show an apparatus for carrying out the method of the invention,
Figure 1 is a simplified side view, Figure 2 is a front view, Figure 3 is a front view showing various shapes of the pinch roller, Figure 4 is a simplified front view of the tube rotating at high speed, and Figure 5. 6 is a simplified front view in the case of using an irregularly shaped rotating roller, and FIG. 6 is a longitudinal sectional side view of the main part of the tube body with the inner surface coated. 2, 3...Rotating roller, 8...Pinch loaf,
10... Steel pipe, 12... Paint film. Scum, next Z Kazeji 3 Kyousuji Kyousuji J Kyousuji 〆Kyo

Claims (1)

[Claims] 1. Rotating a tube body with internal coating at high speed in the circumferential direction while the paint layer is not dry, applying a centrifugal force of 20 G or more to the paint layer and applying shocks or vibrations to the tube body at a rate of 50 times/second or more. A method for painting the inner surface of a pipe body, characterized by: